This invention relates to a process and apparatus for stopping the attenuating action of a draw frame whenever an end or sliver passing therethrough breaks or otherwise fails properly to pass between the drafting rolls of the machine.
As is known, draw frames are employed to attenuate, parallelize and blend a plurality of slivers or ends, thus producing a combined sliver or roving representative of the characteristics of the various slivers which have been combined. In these machines a plurality of fibers made from varying grades of cotton or other materials is fed simultaneously, in parallel fashion, through the drawing rolls of the machine. The emerging, combined, single sliver or roving thus represents a true mixture of all of the fibers fed into the apparatus.
The machines in question also customarily have been equipped with suction hoods over the entire drafting sections thereof. These hoods or compartments are connected to a suction system leading to a collector for dust, fly, trash and the like which may be discharged during the drafting operation. In view of this arrangement whenever one of the slivers or ends being fed into the draw frame breaks, that end is drawn by the suction away from the normal flow of the material being drafted and proceeds to the collector via the suction fan. It has been found that ends or slivers may break in these machines and go unnoticed for a considerable length of time. This results in the production of light-weight, unsuitable sliver, the short weight of which eventually is reflected in the finished yarn. Also, if permitted to go on for a long enough time, these down ends cause chokes in the suction system. So far as I am aware, there heretofore has been no suitable way to warn the operator that an end is down inside the hood and that the machine should be stopped.
My invention relates to means automatically to shut down the drafting frame whenever an end or sliver mis-feeds or breaks.
Briefly, my invention comprises a sensor having a field of influence located at a point in the suction system by which a broken sliver passes on its way out of the apparatus, into the collector. The field of influence through which the broken end passes generates a signal upon the presence of the end passing through said field of influence. Further, in view of the fact that during normal operation of draw frames of the kind described, there is a discharge of fly, dust, trash and the like, I so design the sensor that it is responsive only to the presence of sliver as distinguished from the aforementioned particles being discharged.
In view of the foregoing it will be seen that an object of my invention is to provide an economical, efficient process and apparatus for automatically stopping draw frames and the like upon the mis-drawing or breaking of an end or sliver passing therethrough.
A more detailed object is to provide a guide for the sliver located in the suction duct which is effective to cause the broken end to pass into the field of influence of a sensor, thus assuring that the sensor produces a signal indicative of the presence of a broken end.
Another object is to provide a process of the character designated in which a broken end is moved away from the normal path of movement of the ends passing through the drawing apparatus, preferably generally normal to said path, passed through a field of influence, thus to generate a signal, and using that signal to shut down the drawing frame and to shut down the suction fan, if each individual draw frame is equipped with a suction fan as distinguished from being tied into a system where one fan serves more than one draw frame.